Novel interference pigments

ABSTRACT

The present invention relates to pigments, comprising (A) optionally a layer consisting of a metal, (B) at least one layer, which is located between the layers (A) and (C), if a layer (A) is 5 present, and consists of the metal, silicon (Si) and oxygen (O), and (C) optionally a layer consisting of SiO z  with 0.70≦z≦2.0 on layer (B), a process for the production of the pigments and their use in ink-jet printing, for dyeing textiles, for pigmenting coatings, paints, printing inks, plastics, cosmetics, glazes for ceramics and glass.

The present Invention relates to (interference) pigments, comprising atleast one layer, which is obtained by calcining of a metal and SiO_(z)with 0.70≦z≦2.0, especially 1.1≦z≦2.0, a method of producing thepigments and their use in ink-jet printing, for dyeing textiles, forpigmenting coatings, printing inks, plastics, cosmetics, glazes forceramics and glass.

WO93/19131 disclose platelet-shaped colored pigments containing titaniumdioxide, one or more suboxides of titanium and an oxide or oxides of oneor more metals other than titanium or non-metals, wherein theconcentration of the titanium oxides in the coating layer is maximum inthe proxity of the substrate surface and gradually decreases toward thepigment surface.

WO00/34395, WO00/69975 and WO02/31058 describe bright metal flakes,SiO_(y1)/Al/SiO_(y1), wherein y1 is from about 1 to about 2. Thethickness of the aluminum layer is at least about 40 nm and thethickness of the SiO_(y1) layer is at least 10 nm.

WO03/68868 describes a process for producing SiO_(y) flakes. The SiO_(y)flakes may be treated with a carbon-containing gas at from 500 to 1500°C., preferably from 500 to 1000° C., preferably with the exclusion ofoxygen, wherein a SiC layer is formed on the SiO_(y) flakes.Alternatively the SiO_(y) flakes can be converted in SiO₂ flakes byheating them in an oxygen-containing atmosphere. The SiO₂ flakes can beused as substrates for interference pigments.

PCT/EP03/09296 discloses platelet-shaped pigments comprising a layerobtained by calcining TiO₂/SiO_(z), wherein 0.03≦z≦2.0, and their use inpaints, textiles, ink-jet printing, cosmetics, coatings, plasticsmaterials, printing inks, in glazes for ceramics and glass, and insecurity printing.

EP-A-803549 discloses coloured pigments containing (a) a core consistingof an essentially transparent or metallic reflecting material, and (b)at least a coating consisting essentially of one or more siliconeoxides, the molar ratio of oxygen to a silicon being 0.25 to 0.95.

Surprisingly, it was found, that (colored) pigments could be obtained,if plane-parallel structures (flakes), comprising (A) at least one layerconsisting of a metal and (C) at least one layer consisting of SiO_(z)with 0.70≦z≦2.0, especially 1.1≦z≦2.0, are calcined in a non-oxidizingatmosphere.

It is assumed, that by calcining of metal/SiO_(y) in a non-oxidizingatmosphere a layer, i.e. a layer (B), or a composite layer, layer(B)/layer (A)/layer (B) is obtained, whereby a change of the refractiveindex is caused. It is assumed, that the change of the refractive indexis based on the oxidation of the metal by SiO_(y). It is, for example,known that by heating of SiO and aluminum at 650° C. Si and Al₂O₃ areformed and that by heating of SiO and titanium at 900° C. titaniumsilicides are formed (New J. Chem., 2001, 25, 994-998).

Accordingly, the present invention relates to a pigment, comprising (A)optionally a layer consisting of a metal, (B) at least one layer, whichis located between the layers (A) and (C), if a layer (A) is present,and consists of the metal, silicon (Si) and oxygen (O), and (C)optionally a layer consisting of SiO_(z) with 0.70≦z—2.0 on layer (B).The layer (B) is obtained by calcining pigments comprising (A) a layerconsisting of a metal, and (C) a layer consisting of SiO_(y) on themetal layer, with 0.70≦y≦1.80, in a non-oxidizing atmosphere at atemperature above 600° C.

Pigments, which do not contain a layer (A) are preferred. That is,preferably the whole layer (A) is converted to the layer (B) duringcalcination in the non-oxidizing atmosphere.

The term “SiO_(z) with 0.70≦z≦2.0” means that the molar ratio of oxygento silicon at the average value of the silicon oxide layer is from 0.70to 2.0. The composition of the silicon oxide layer can be determined byESCA (electron spectroscopy for chemical analysis).

The term “SiO_(y) with 0.70≦y≦1.8” means that the molar ratio of oxygento silicon at the average value of the silicon oxide layer is from 0.70to 1.80. The composition of the silicon oxide layer can be determined byESCA (electron spectroscopy for chemical analysis).

According to the present invention the term “aluminum” comprisesaluminum and alloys of aluminum. Alloys of aluminum are, for example,described in G. Wassermann in Ullmanns Enzyklopädie der IndustriellenChemie, 4. Auflage, Verlag Chemie, Weinheim, Band 7, S. 281 to 292.Especially suitable are the corrosion stable aluminum alloys describedon page 10 to 12 of WO00/12634, which comprise besides of aluminumsilicon, magnesium, manganese, copper, zinc, nickel, vanadium, lead,antimony, tin, cadmium, bismuth, titanium, chromium and/or iron inamounts of less than 20% by weight, preferably less than 10% by weight.

To further increases the light weather and chemical stability, theSiO_(y) layer may be oxidized using an oxygen-containing gas such as,for example, air at a temperature of at least 200° C., especially atabove 400° C., preferably in the form of loose material, in a fluidizedbed or by introduction into an oxidizing flame, preferably at atemperature in the range from 500 to 100° C.

A further subject of the present invention is the use of the pigments inink-jet printing (EP 02405888), for dyeing textiles (EP 02405889), forpigmenting coatings, printing inks, plastics, cosmetics(PCT/EP03/09296), glazes for ceramics and glass and in securityprinting.

The pigments of the present invention are particles, which generallyhave a length of from 2 μm to 5 mm, a width of from 2 μm to 2 mm, and athickness of from 20 nm to 2 μm, and a ratio of length to thickness ofat least 2:1, wherein the particles contain a core having twosubstantially parallel faces, the distance between which is the shortestaxis of the core, and further layers which have been deposited on theparallel faces, but not on the side surface, or on the whole surface ofthe pigments. The pigments of the present invention are characterized bythe precisely defined thickness and smooth surface.

The metal of layer (A) can be, in principal, any metal that at thecalcining step reacts with SiO_(y) to form the layer (B). Ag, Al, Cu,Cr, Mo, Ni, Ti or alloys thereof are preferred, wherein Al is mostpreferred.

Preferably layer (A) or, if layer (A) is absent, layer (B) forms thecore of the pigment. If layer (A) forms the core, additional layers (B)and/or (C) can be present only on one parallel face or on both parallelfaces of the pigment (A/B/C or C/B/A/B/C). If layer (A) is absent andlayer (B) forms the core, layer (C) can be present on only one parallelface or on both parallel faces of the pigment (B/C or C/B/C). The layers(B), if a layer (A) is present, and (C) are preferably arranged insymmetrical order around the core. The layers (B) and/or (C) arranged insymmetrical order around the core can have different thicknesses, buthave preferably the same thickness.

If Al/SiO_(y)/Al flakes are calcined in a non-oxidising atmosphere thefollowing pigments and/or substrates for (interference pigments) can beobtained:

(A1) a layer consisting of a metal, especially aluminum,

(B) a layer arranged between the layers (A1) and (A2) and consisting ofmetal, Si and O, and

(A2) a layer consisting of a metal, especially aluminum; or

(A1) a layer consisting of a metal, especially aluminum,

(B1) a layer arranged between the layers (A1) and (C) and consisting ofmetal, Si and O,

(C) a layer consisting of SiO_(y),

(B2) a layer arranged between the layers (C) and (A2) and consisting ofmetal, Si and O, and

(A2) a layer consisting of a metal, especially aluminum.

In a preferred embodiment the pigment comprises

(C1) a layer consisting of SiO_(y),

(B) a layer arranged between the layers (C1) and (C2) and consisting ofmetal, Si and O, and

(C2) a layer consisting of SiO_(y).

The SiO_(y) of layers (C1) and (C2) may be oxidised using anoxygen-containing gas such as, for example, air at a temperature of atleast 200° C., especially at above 400° C., preferably in the form ofloose material, in a fluidised bed or by introduction into an oxidisingflame, preferably at a temperature in the range from 500 to 1000° C.,resulting in pigments, comprising

(C1) a layer consisting of SiO_(z),

(B) a layer arranged between the layers (C1) and (C2) and consisting ofmetal, Si and O, and

(C2) a layer consisting of SiO_(z).

In this embodiment the layer (B) preferably forms the core of thepigment, wherein (C1) and (C2) are only present on the parallel faces ofthe core.

In a further preferred embodiment the pigment comprises

(C1) a layer consisting of SiO_(z),

(B1) a layer arranged between the layers (C1) and (A) and consisting ofmetal, Si and O,

(A) a layer consisting of a metal, especially aluminum,

(B2) a layer arranged between the layers (A) and (C2) and consisting ofmetal, Si and O, and

(C2) a layer consisting of SiO_(z); which is obtainable by calcining ofSiO_(y)/metal/SiO_(y) flakes in a non-oxidizing atmosphere.

In this embodiment the layer (A) preferably forms the core of thepigment, wherein (B1), (B2), (C1) and (C2) are only present on theparallel faces of the core.

Colored (interference) pigments having high color strength and colorpurity can be obtained when the above pigments are coated with amaterial of high refractive index.

Accordingly, in a further embodiment the present invention relates tocolored (interference) pigments, comprising

(D1) a layer of a material of high refractive index, especially TiO₂,

(C1) a layer consisting of SiO_(z),

(B) a layer arranged between the layers (C1) and (C2) and consisting ofmetal, Si and O, and

(C2) a layer consisting of SiO_(z), and

(D2) a layer of a material of high refractive index, especially TiO₂,wherein 0.70≦z—2.0, especially 1.10≦z≦2.0, more especially 1.40≦z≦2.0.

In this embodiment the layer (B) preferably forms the core of thepigment, wherein (C1) and (C2) are only present on the parallel faces ofthe core. The layer (D2) of the material of high refractive index,especially TiO₂, can be present only on layers (C1) and (C2), but ispreferably present on the whole surface of the pigment.

In one preferred embodiment of the present invention, the interferencepigments comprise materials having a “high” index of refraction, whichis defined herein as an index of refraction of greater than about 1.65,and optionally materials having a “low” index of refraction, which isdefined herein as an index of refraction of about 1.65 or less. Various(dielectric) materials that can be utilized include inorganic materialssuch as metal oxides, metal suboxides, metal fluorides, metaloxyhalides, metal sulfides, metal chalcogenides, metal nitrides, metaloxynitrides, metal carbides, combinations thereof, and the like, as wellas organic dielectric materials. These materials are readily availableand easily applied by physical, or chemical vapor deposition processes,or by wet chemical coating processes.

In an especially preferred embodiment, the interference pigments on thebasis of the silicon oxide/metal substrate comprises a further layer ofa dielectric material having a “high” refractive index, that is to say arefractive index greater than about 1.65, preferably greater than about2.0, most preferred greater than about 2.2, which is applied to theentire surface of the silicon oxide/metal substrate. Examples of such adielectric material are zinc sulfide (ZnS), zinc oxide (ZnO), zirconiumoxide (ZrO₂), titanium dioxide (TiO₂), carbon, indium oxide (In₂O₃),indium tin oxide (ITO), tantalum pentoxide (Ta₂O₅), chromium oxide(Cr₂O₃), cerium oxide (CeO₂), yttrium oxide (Y₂O₃), europium oxide(Eu₂O₃), iron oxides such as iron(II)/iron(III) oxide (Fe₃O₄) andiron(III) oxide (Fe₂O₃), hafnium nitride (HfN), hafnium carbide (HfC),hafnium oxide (HfO₂), lanthanum oxide (La₂O₃), magnesium oxide (MgO),neodymium oxide (Nd₂O₃), praseodymium oxide (Pr₆O₁₁), samarium oxide(Sm₂O₃), antimony trioxide (Sb₂O₃), silicon monoxides (SiO), seleniumtrioxide (Se₂O₃), tin oxide (SnO₂), tungsten trioxide (WO₃), orcombinations thereof. The dielectric material is preferably a metaloxide. It being possible for the metal oxide to be a single oxide or amixture of oxides, with or without absorbing properties, for example,TiO₂, ZrO₂, Fe₂O₃, Fe₃O₄, Cr₂O₃, iron titanate, iron oxide hydrates,titanium suboxides, or ZnO₁ with TiO₂ being especially preferred.

It is possible to obtain pigments that are more intense in color andmore transparent by applying, on top of the TiO₂ layer, a metal oxide oflow refractive index. Nonlimiting examples of suitable low indexdielectric materials that can be used include silicon dioxide (SiO₂),aluminum oxide (Al₂O₃), and metal fluorides such as magnesium fluoride(MgF₂), aluminum fluoride (AlF₃), cerium fluoride (CeF₃), lanthanumfluoride (LaF₃), sodium aluminum fluorides (e.g., Na₃AlF₆ or Na₅Al₃F₁₄),neodymium fluoride (NdF₃), samarium fluoride (SmF₃), barium fluoride(BaF₂), calcium fluoride (CaF₂), lithium fluoride (LiF), combinationsthereof, or any other low index material having an index of refractionof about 1.65 or less. For example, organic monomers and polymers can beutilized as low index materials, including dienes or alkenes such asacrylates (e.g., methacrylate), polymers of perfluoroalkenes,polytetrafluoroethylene (TEFLON), polymers of fluorinated ethylenepropylene (FEP), parylene, p-xylene, combinations thereof, and the like.Additionally, the foregoing materials include evaporated, condensed andcross-linked transparent acrylate layers, which may be deposited bymethods described in U.S. Pat. No. 5,877,895, the disclosure of which isincorporated herein by reference. SiO₂, Al₂O₃, AlOOH, B₂O₃, or a mixturethereof, are preferred. SiO₂ is most preferred.

The metal oxide layers can be applied by CVD (chemical vapourdeposition) or by wet chemical coating. The metal oxide layers can beobtained by decomposition of metal carbonyls in the presence of watervapour (relatively low molecular weight metal oxides such as magnetite)or in the presence of oxygen and, where appropriate, water vapour (e.g.nickel oxide and cobalt oxide). The metal oxide layers are especiallyapplied by means of oxidative gaseous phase decomposition of metalcarbonyls (e.g. iron pentacarbonyl, chromium hexacarbonyl; EP-A45 851),by means of hydrolytic gaseous phase decomposition of metal alcoholates(e.g. titanium and zirconium tetra-n- and -iso-propanolate; DE-A-41 40900) or of metal halides (e.g. titanium tetrachloride; EP-A-338 428), bymeans of oxidative decomposition of organyl tin compounds (especiallyalkyl tin compounds such as tetrabutyltin and tetramethyltin; DE-A-44 03678) or by means of the gaseous phase hydrolysis of organyl siliconcompounds (especially di-tert-butoxyacetoxysilane) described in EP-A-668329, it being possible for the coating operation to be carried out in afluidised bed reactor (EP-A-045 851 and EP-A-106 235). Al₂O₃ layers (B)can advantageously be obtained by controlled oxidation during thecooling of aluminium-coated pigments, which is otherwise carried outunder inert gas (DE-A-195 16 181).

Phosphate-, chromate- and/or vanadate-containing and also phosphate- andSiO₂-containing metal oxide layers can be applied in accordance with thepassivation methods described in DE-A42 36 332 and in EP-A-678 561 bymeans of hydrolytic or oxidative gaseous phase decomposition ofoxide-halides of the metals (e.g. CrO₂Cl₂, VOCl₃), especially ofphosphorus oxyhalides (e.g. POCl₃), phosphoric and phosphorous acidesters (e.g. di- and tri-methyl and di- and tri-ethyl phosphite) and ofamino-group-containing organyl silicon compounds (e.g.3-aminopropyl-triethoxy- and -trimethoxy-silane).

Layers of oxides of the metals zirconium, titanium, iron and zinc, oxidehydrates of those metals, iron titanates, titanium suboxides or mixturesthereof are preferably applied by precipitation by a wet chemicalmethod, it being possible, where appropriate, for the metal oxides to bereduced. In the case of the wet chemical coating, the wet chemicalcoating methods developed for the production of pearlescent pigments maybe used; these are described, for example, in DE-A-14 67 468, DE-A-19 59988, DE-A-20 09 566, DE-A-22 14 545, DE-A-22 15 191, DE-A-22 44 298,DE-A-23 13 331, DE-A-25 22 572, DE-A-31 37 808, DE-A-31 37 809, DE-A-3151 343, DE-A-31 51 354, DE-A-31 51 355, DE-A-32 11 602 and DE-A-32 35017, DE 195 99 88, WO 93/08237, WO 98/53001 and WO03/6558.

The metal oxide of high refractive index is preferably TiO₂ and/or ironoxide, and the metal oxide of low refractive index is preferably SiO₂.Layers of TiO₂ can be in the rutile or anastase modification, whereinthe rutile modification is preferred. TiO₂ layers can also be reduced byknown means, for example ammonia, hydrogen, hydrocarbon vapor ormixtures thereof, or metal powders, as described in EP-A-735,114,DE-A-3433657, DE-A-4125134, EP-A-332071, EP-A-707,050 or WO93/19131.

For the purpose of coating, the substrate particles are suspended inwater and one or more hydrolysable metal salts are added at a pHsuitable for the hydrolysis, which is so selected that the metal oxidesor metal oxide hydrates are precipitated directly onto the particleswithout subsidiary precipitation occurring. The pH is usually keptconstant by simultaneously metering in a base. The pigments are thenseparated off, washed, dried and, where appropriate, calcinated, itbeing possible to optimise the calcinating temperature with respect tothe coating in question. If desired, after individual coatings have beenapplied, the pigments can be separated off, dried and, whereappropriate, calcinated, and then again re-suspended for the purpose ofprecipitating further layers.

The metal oxide layers are also obtainable, for example, in analogy to amethod described in DE-A-195 01 307, by producing the metal oxide layerby controlled hydrolysis of one or more metal acid esters, whereappropriate in the presence of an organic solvent and a basic catalyst,by means of a sol-gel process. Suitable basic catalysts are, forexample, amines, such as triethylamine, ethylenediamine, tributylamine,dimethylethanolamine and methoxy-propylamine. The organic solvent is awater-miscible organic solvent such as a C₁₋₄alcohol, especiallyisopropanol.

Suitable metal acid esters are selected from alkyl and aryl alcoholates,carboxylates, and carboxyl-radical- or alkyl-radical- oraryl-radical-substituted alkyl alcoholates or carboxylates of vanadium,titanium, zirconium, silicon, aluminium and boron. The use oftriisopropyl aluminate, tetraisopropyl titanate, tetraisopropylzirconate, tetraethyl orthosilicate and triethyl borate is preferred. Inaddition, acetylacetonates and acetoacetylacetonates of theaforementioned metals may be used. Preferred examples of that type ofmetal acid ester are zirconium acetylacetonate, aluminiumacetylacetonate, titanium acetylacetonate and diisobutyloleylacetoacetylaluminate or diisopropyloleyl acetoacetylacetonate andmixtures of metal acid esters, for example Dynasil® (Hüls), a mixedaluminium/silicon metal acid ester.

As a metal oxide having a high refractive index, titanium dioxide ispreferably used, the method described in US-B-3 553 001 being used, inaccordance with an embodiment of the present invention, for applicationof the titanium dioxide layers.

An aqueous titanium salt solution is slowly added to a suspension of thematerial being coated, which suspension has been heated to about 50-100°C., especially 70-80° C., and a substantially constant pH value of aboutfrom 0.5 to 5, especially about from 1.2 to 2.5, is maintained bysimultaneously metering in a base such as, for example, aqueous ammoniasolution or aqueous alkali metal hydroxide solution. As soon as thedesired layer thickness of precipitated TiO₂ has been achieved, theaddition of titanium salt solution and base is stopped.

This method, also referred to as a titration method, is distinguished bythe fact that an excess of titanium salt is avoided. That is achieved byfeeding in for hydrolysis, per unit time, only that amount which isnecessary for even coating with the hydrated TiO₂ and which can be takenup per unit time by the available surface of the particles being coated.In principle, the anatase form of TiO₂ forms on the surface of thestarting pigment. By adding small amounts of SnO₂, however, it ispossible to force the rutile structure to be formed. For example, asdescribed in WO 93/08237, tin dioxide can be deposited before titaniumdioxide precipitation and the product coated with titanium dioxide canbe calcined at from 800 to 900° C.

The TiO₂ can optionally be reduced by usual procedures: U.S. Pat. No.4,948,631 (NH₃, 750-850° C), WO93/19131 (H₂, >900° C.) or DE-A-19843014(solid reduction agent, such as, for example, silicon, >600° C.).

Where appropriate, an SiO₂ (protective) layer can be applied on top ofthe titanium dioxide layer, for which the following method may be used:A soda waterglass solution is metered in to a suspension of the materialbeing coated, which suspension has been heated to about 50-100° C.,especially 70-80° C. The pH is maintained at from 4 to 10, preferablyfrom 6.5 to 8.5, by simultaneously adding 10% hydrochloric acid. Afteraddition of the waterglass solution, stirring is carried out for 30minutes.

It is possible to obtain pigments that are more intense in colour andmore transparent by applying, on top of the TiO₂ layer, a metal oxide of“low” refractive index, that is to say a refractive index smaller thanabout 1.65, such as SiO₂, Al₂O₃, AlOOH, B₂O₃ or a mixture thereof,preferably SiO₂, and applying a further Fe₂O₃ and/or TiO₂ layer on topof the latter layer. Such multi-coated interference pigments comprisinga silicon oxide/metal substrate and alternating metal oxide layers ofwith high and low refractive index can be prepared in analogy to theprocesses described in WO98/53011 and WO99/20695.

It is, in addition, possible to modify the powder colour of the pigmentby applying further layers such as, for example, coloured metal oxidesor Berlin Blue, compounds of transition metals, e.g. Fe, Cu, Ni, Co, Cr,or organic compounds such as dyes or colour lakes.

In addition, the pigment according to the invention can also be coatedwith poorly soluble, firmly adhering, inorganic or organic colourants.Preference is given to the use of colour lakes and, especially,aluminium colour lakes. For that purpose an aluminium hydroxide layer isprecipitated, which is, in a second step, laked by using a colour lake(DE-A-24 29 762 and DE 29 28 287).

Furthermore, the pigment according to the invention may also have anadditional coating with complex salt pigments, especially cyanoferratecomplexes (EP-A-141 173 and DE-A-23 13 332).

To enhance the weather and light stability the multilayer silicon oxideflakes can be, depending on the field of application, subjected to asurface treatment. Useful surface treatments are, for example, describedin DE-C-2215191, DE-A-3151354, DE-A-3235017, DE-A-3334598, DE-A-4030727,EP-A-649886, WO97/29059, WO99/57204, and U.S. Pat. No. 5,759,255. Saidsurface treatment might also facilitate the handling of the pigment,especially its incorporation into various application media.

Instead of the layer of the material having a high index of refraction asemitransparent metal layer can be applied. Suitable metals for thesemi-transparent metal layer are, for example, Cr, Ti, Mo, W, Al, Cu,Ag, Au, or Ni. The semi-transparent metal layer has typically athickness of between 5 and 25 nm, especially between 5 and 15 nm. Thesemitransparent metal layer can be applied by PVD.

Alternatively the metal layer can be obtained by wet chemical coating orby chemical vapor deposition, for example, gas phase deposition of metalcarbonyls. The substrate is suspended in an aqueous and/or organicsolvent containing medium in the presence of a metal compound and isdeposited onto the substrate by addition of a reducing agent. The metalcompound is, for example, silver nitrate or nickel acetyl acetonate(WO03/37993).

According to U.S. Pat. No. 3,536,520 nickel chloride can be used asmetal compound and hypophosphite can be used as reducing agent.According to EP-A-353544 the following compounds can be used as reducingagents for the wet chemical coating: aldehydes (formaldehyde,acetaldehyde, benzalaldehyde), ketones (acetone), carboxylic acids andsalts thereof (tartaric acid, ascorbic acid), reductones (isoascorbicacid, triosereductone, reductic acid), and reducing sugars (glucose).

In another preferred embodiment of the present invention layer (B) inthe above described preferred embodiments can be replaced by a structurelayer (B)/Layer (A)/layer (B), wherein instead of layer (B) layer(B)/Layer (A)/layer (B) forms the core of the pigment,

If in the above decribed embodiments aluminum is used as metal, thethickness of layer (B) and/or layer (A) and (B), if layer (A) ispresent, is generally in the range of 5 to 100 nm, especially 30 to 60nm.

The thickness of the SiO_(z) layer (0.70≦z≦2.0) is generally 10 to 1000nm. The preferred thickness of the SiO_(z) layer depends on the desiredcolor. Thicknesses of the SiO_(z) layer above 500 nm lead to mattcolors.

The TiO₂ layer is preferably deposited by a wet chemical process. Thethickness of the TiO₂ layer is generally 5 to 200 nm, especially 10 to100 nm, more especially 20 to 50 nm. The present invention isillustrated in more detail on the basis of aluminum as metal and TiO₂ asmaterial of high refractive index.

The Al flakes coated with SiO_(y) are prepared by a process comprisingthe following steps (EP-B-990715):

a) vapor-deposition of a separating agent onto a (movable) carrier toproduce a separating agent layer,

b) deposition-deposition of an SiO_(y) layer onto the separating agentlayer, wherein 0.70≦y≦1.80,

c) deposition-deposition of an Al layer onto the SiO_(y) layer,

d) deposition of an SiO_(y) layer onto the Al layer,

e) dissolution of the separating agent layer in a solvent, and

f) separation of the SiO_(y) from the solvent.

The SiO_(y) layer being deposited-deposited from a vaporizer containinga charge comprising a mixture of Si and SiO₂, SiO_(y) or a mixturethereof, the weight ratio of Si to SiO₂ being preferably in the rangefrom 0.15:1 to 0.75:1, and especially containing a stoichiometricmixture of Si and SiO₂. The SiO_(1.00-1.8) layer is formed preferablyfrom silicon monoxide vapour produced in the vaporiser by reaction of amixture of Si and SiO₂ at temperatures of more than 1300° C. TheSiO_(0.70-0.99) layer is formed preferably by evaporating siliconmonoxide containing silicon in an amount up to 20% by weight attemperatures of more than 1300° C.

The Al flakes coated with SiO_(y) according to the above process have ahigh plane-parallelism and a defined thickness in the range of ±10%,especially ±5% of the average thickness and low reflectivity.

The SiO_(y) layer in step b) and d) being deposited-deposited from avaporizer containing a charge comprising a mixture of Si and SiO₂,SiO_(y) or a mixture thereof, the weight ratio of Si to SiO₂ beingpreferably in the range from 0.15:1 to 0.75:1, and especially containinga stoichiometric mixture of Si and SiO₂. Step e) being advantageouslycarried out at a pressure that is higher than the pressure in steps a)and b) and lower than atmospheric pressure. The SiO_(y)-coated Al flakesobtainable by this method have a thickness in the range preferably from20 to 2000 nm, especially from 20 to 500 nm, most preferred from 20 to200 nm, the ratio of the thickness to the surface area of theplane-parallel structures being preferably less than 0.01 μm⁻¹ and theaspect ratio being at least 2:1. The silicon oxide/aluminum flakes arenot of a uniform shape. Nevertheless, for purposes of brevity, theflakes will be referred to as having a “diameter.” The siliconoxide/aluminum flakes have a high plane-parallelism and a definedthickness in the range of ±10%, especially ±5% of the average thickness.The silicon oxide/aluminum flakes have a thickness of from 20 to 2000nm, very especially from 100 to 350 nm. It is presently preferred thatthe diameter of the flakes be in a preferred range of about 1-60 μm witha more preferred range of about 5-40 μm. Thus, the aspect ratio of theflakes of the present invention is in a preferred range of about 14 to400.

The silicon oxide layer (SiO_(y)) in step b) and d) is formed preferablyfrom silicon monoxide vapor produced in the vaporizer by reaction of amixture of Si and SiO₂ at temperatures of more than 1300° C. TheSiO_(0.70-0.99) layer is formed preferably by evaporating siliconmonoxide containing silicon in an amount up to 20% by weight attemperatures of more than 1300° C.

The deposition-deposition in steps a) and b) is carried out preferablyunder a vacuum of <0.5 Pa. The dissolution of the separating agent layerin step e) is carried out at a pressure in the range preferably from 1to 5×10⁴ Pa, especially from 600 to 10⁴ Pa, and more especially from 10³to 5×10³ Pa.

The separating agent deposited-deposited onto the carrier in step a) maybe a lacquer, a polymer, such as, for example, the (thermoplastic)polymers, in particular acryl- or styrene polymers or mixtures thereof,as described in U.S. Pat. No. 6,398,999, an organic substance soluble inorganic solvents or water and vaporizable in vacuo, such as anthracene,anthraquinone, acetamidophenol, acetylsalicylic acid, camphoricanhydride, benzimidazole, benzene-1,2,4-tricarboxylic acid,biphenyl-2,2-dicarboxylic acid, bis(4-hydroxyphenyl)sulfone,dihydroxyanthraquinone, hydantoin, 3-hydroxybenzoic acid,8-hydroxyquinoline-5-sulfonic acid monohydrate, 4-hydroxycoumarin,7-hydroxycoumarin, 3-hydroxynaphthalene-2-carboxylic acid, isophthalicacid, 4,4-methylene-bis-3-hydroxynaphthalene-2-carboxylic acid,naphthalene-1,8-dicarboxylic anhydride, phthalimide and its potassiumsalt, phenolphthalein, phenothiazine, saccharin and its salts,tetraphenylmethane, triphenylene, triphenylmethanol or a mixture of atleast two of those substances. The separating agent is preferably aninorganic salt soluble in water and vaporizable in vacuo (see, forexample, DE 198 44 357), such as sodium chloride, potassium chloride,lithium chloride, sodium fluoride, potassium fluoride, lithium fluoride,calcium fluoride, sodium aluminium fluoride and disodium tetraborate.

The movable carrier may consist of one or more discs, cylinders or otherrotationally symmetrical bodies, which rotate about an axis (cf.WO01/25500), and consists preferably of one or more continuous metalbelts with or without a polymeric coating or of one or more polyimide orpolyethylene terephthalate belts (U.S. Pat. No. 6,270,840).

Step f) may comprise washing-out and subsequent filtration,sedimentation, centrifugation, decanting and/or evaporation. Theplane-parallel structures of SiO_(y) may, however, also be frozentogether with the solvent in step d) and subsequently subjected to aprocess of freeze-drying, whereupon the solvent is separated off as aresult of sublimation below the triple point and the dry SiO_(y) remainsbehind in the form of individual plane-parallel structures.

Except under an ultra-high vacuum, in technical vacuums of a few 10⁻² Pavaporized SiO always condenses as SiO_(y) wherein 1≦y≦1.8, especiallywherein 1.1≦y≦1.8, because high-vacuum apparatuses always contain, as aresult of gas emission from surfaces, traces of water vapor which reactwith the readily reactive SiO at vaporization temperature.

On its further course, the belt-form carrier, which is closed to form aloop, runs through dynamic vacuum lock chambers of known mode ofconstruction (cf. U.S. Pat. No. 6,270,840) into a region of from 1 to5×10⁴ Pa pressure, preferably from 600 to 10⁴ Pa pressure, andespecially from 10³ to 5×10³ Pa pressure, where it is immersed in adissolution bath. The temperature of the solvent should be so selectedthat its vapor pressure is in the indicated pressure range. Withmechanical assistance, the separating agent layer rapidly dissolves andthe product layer breaks up into flakes, which are then present in thesolvent in the form of a suspension. On its further course, the belt isdried and freed from any contaminants still adhering to it. It runsthrough a second group of dynamic vacuum lock chambers back into thevaporization chamber, where the process of coating with separating agentand product layer of SiO_(y)/Al/SiO_(y) is repeated.

The suspension then present in both cases, comprising product structuresand solvent, and the separating agent dissolved therein, is thenseparated in a further operation in accordance with a known technique.For that purpose, the product structures are first concentrated in theliquid and rinsed several times with fresh solvent in order to wash outthe dissolved separating agent. The product, in the form of a solid thatis still wet, is then separated off by filtration, sedimentation,centrifugation, decanting or evaporation.

The product can then be brought to the desired particle size by means ofultrasound or by mechanical means using high-speed stirrers in a liquidmedium, or after drying the fragments in an air-jet mill having a rotaryclassifier, or means of grinding or air-sieving and delivered forfurther use.

In detail, a salt, for example NaCl, followed by layers of siliconsuboxide (SiO_(y)), aluminum and SiO_(y) are successivelydeposited-deposited onto a carrier, which may be a continuous metalbelt, passing by way of the vaporizers under a vacuum of <0.5 Pa. Thedeposited-deposited thicknesses of salt are approximately from 20 to 100nm, preferably from 30 to 60 nm, and those of SiO are, depending on theintended use of the product, from 10 to 1000 nm, and those of aluminumfrom 10 to 100 nm.

On its further course, the belt-form carrier, which is closed to form aloop, runs through dynamic vacuum lock chambers of known mode ofconstruction (cf. U.S. Pat. No. 6,270,840) into a region of from 1 to5×10⁴ Pa pressure, preferably from 600 to 10⁴ Pa pressure, andespecially from 10³ to 5×10³ Pa pressure, where it is immersed in adissolution bath. The temperature of the solvent should be so selectedthat its vapor pressure is in the indicated pressure range. Withmechanical assistance, the separating agent layer rapidly dissolves andthe product layer breaks up into flakes, which are then present in thesolvent in the form of a suspension. On its further course, the belt isdried and freed from any contaminants still adhering to it. It runsthrough a second group of dynamic vacuum lock chambers back into thevaporization chamber, where the process of coating with separating agentand product layer of SiO is repeated.

The suspension then present in both cases, comprising product structuresand solvent, and the separating agent dissolved therein, is thenseparated in a further operation in accordance with a known technique.For that purpose, the product structures are first concentrated in theliquid and rinsed several times with fresh solvent in order to wash outthe dissolved separating agent. The product, in the form of a solid thatis still wet, is then separated off by filtration, sedimentation,centrifugation, decanting or evaporation.

The product can then be brought to the desired particle size by means ofultrasound or by mechanical means using high-speed stirrers in a liquidmedium, or after drying the fragments in an air-jet mill having a rotaryclassifier, or means of grinding or air-sieving and delivered forfurther use.

Separating off the plane-parallel structures after washing-out atatmospheric pressure can be carried out under gentle conditions byfreezing the suspension, which has been concentrated to a solids contentof about 50%, and subjectng it in known manner to freeze-drying at about−10° C. and 50 Pa pressure. The dry substance remains behind as product,which can be subjected to the steps of further processing by means ofcoating or chemical conversion.

Hence, a further aspect of the present invention is formed byplane-parallel structures, comprising (A) a layer consisting of a metal,especially aluminum, and (C) at least one layer consisting of SiO_(z),wherein 0.70≦z≦2.0, especially 1.10≦z≦2.0, more especially 1.40≦z≦2.0.

For the further processing of the Al flakes coated with SiO_(y)different variants are possible:

Variant (1): calcination in a non-oxidizing atmosphere (→layer (B)),calcination in the presence of oxygen (SiO_(z)→SiO₂) and optionallycoating of the obtained pigments with TiO₂(TiO₂/SiO_(z)/core/SiO_(z)/TiO₂), wherein core=layer (B) or layer(B)/layer (A)/layer (B).

Variant (2): calcination in a non-oxidizing atmosphere (→layer (B)),coating of the obtained pigments with TiO₂(TiO₂/SiO_(y)/core/SiO_(y)/TiO₂) and optionally calcination in thepresence of oxygen (SiO_(y)→SiO_(z)) (TiO₂/SiO_(z)/core/SiO_(z)/TiO₂).

Variant (3): calcination in a non-oxidizing atmosphere (→layer (B)),coating of the obtained pigments with TiO₂, calcination in anon-oxidizing atmosphere (→layer (E)) (TiO₂/layer(E)/SiO_(y)/core/SiO_(y)/layer (E)/TiO₂) and optionally calcination inthe presence of oxygen (SiO_(y)→SiO_(z) ) (TiO₂/layer(E)/SiO_(z)/core/SiO_(z)/layer (E)/TiO₂).

Variant (4): coating of the obtained pigments with TiO₂, calcination ina non-oxidizing atmosphere (→layer (B) and layer (E)) (TiO₂/layer(E)/SiO_(y)/Kern/SiO_(y)/layer (E)/TiO₂) and(E)/SiO_(z)/core/SiO_(z)/layer (E)/TiO₂)

The different variants are illustrated in more detail on the basisvariants (1) and (4):

Variant (1) (TiO₂/SiO_(z)/core/SiO_(z)/TiO₂):

The SiO_(y)-coated metal platelets are calcined in a non-oxidizinggaseous atmosphere at a temperature above 600° C., preferably in therange of from 700 to 1100° C. for more then 10 minutes, preferably forseveral hours. The calcination is conducted in a non-oxidizing gaseousatmosphere, such as, for example, Ar and/or He, wherein Ar is preferred,optionally under reduced pressure, preferably a pressure of less than700 Torr (0,9333 10⁵ N/m²).

The SiO_(y)-coated metal platelets can then be subjected to oxidativeheat treatment For example, air or some other oxygen-containing gas ispassed through the platelets, which are in the form of loose material orin a fluidized bed, at a temperature of more than 200° C., preferablymore than 400° C. and especially from 500 to 1000° C., wherein SiO_(y)is oxidized to SiO_(z).

The TiO₂ coating can easily be applied to the SiO_(y)-coated metalplatelets by physical, or chemical vapor deposition processes, or by wetchemical coating processes.

For the purpose of coating, the substrate particles are suspended inwater and one or more hydrolysable titanium salts are added at a pHsuitable for the hydrolysis, which is so selected that the metal oxidesor metal oxide hydrates are precipitated directly onto the particleswithout subsidiary precipitation occurring. The pH is usually keptconstant by simultaneously metering in a base. The pigments are thenseparated off, washed, dried and, where appropriate, calcined, it beingpossible to optimize the calcining temperature with respect to thecoating in question. If desired, after individual coatings have beenapplied, the pigments can be separated off, dried and, whereappropriate, calcined, and then again re-suspended for the purpose ofprecipitating further layers.

The metal oxide layers are obtainable, for example, in analogy to amethod described in DE-A-195 01 307, by producing the titanium oxidelayer by controlled hydrolysis of one or more titanium acid esters,where appropriate in the presence of an organic solvent and a basiccatalyst, by means of a sol-gel process. Suitable basic catalysts are,for example, amines, such as triethylamine, ethylenediamine,tributylamine, dimethylethanolamine and methoxypropylamine. The organicsolvent is a water-miscible organic solvent such as a C₁₋₄alcohol,especially isopropanol.

Suitable titanium acid esters are selected from alkyl and arylalcoholates, carboxylates, and carboxyl-radical- or alkyl-radical- oraryl-radical-substituted alkyl alcoholates or carboxylates of titanium.The use of tetraisopropyl titanate is preferred. In addition,acetylacetonates and acetoacetylacetonates of titanium may be used. Apreferred example of that type of titanium acid ester is titaniumacetylacetonate.

In accordance with an embodiment of the present invention, the methoddescribed in U.S. Pat. No. 3,553,001 is used for application of thetitanium dioxide layers.

An aqueous titanium salt solution is slowly added to a suspension of thematerial being coated, which suspension has been heated to about 50-100°C., especially 70-80° C., and a substantially constant pH value of aboutfrom 0.5 to 5, especially about from 1.2 to 2.5, is maintained bysimultaneously metering in a base such as, for example, aqueous ammoniasolution or aqueous alkali metal hydroxide solution. As soon as thedesired layer thickness of precipitated TiO₂ has been achieved, theaddition of titanium salt solution and base is stopped.

This method, also referred to as a titration method, is distinguished bythe fact that an excess of titanium salt is avoided. That is achieved byfeeding in for hydrolysis, per unit time, only that amount which isnecessary for even coating with the hydrated TiO₂ and which can be takenup per unit time by the available surface of the particles being coated.In principle, the anatase form of TiO₂ forms on the surface of thestarting pigment. By adding small amounts of SnO₂, however, it ispossible to force the rutile structure to be formed. For example, asdescribed in WO 93/08237, tin dioxide can be deposited before titaniumdioxide precipitation and the product coated with titanium dioxide canbe calcined at from 800 to 900° C.

The product can then be brought to the desired particle size by means ofultrasound or by mechanical means using high-speed stirrers in a liquidmedium, or after drying the fragments in an air-jet mill having a rotaryclassifier, or means of grinding or air-sieving and delivered forfurther use.

It is possible for the weathering resistance to be increased by means ofan additional coating, which at the same time causes an optimaladaptation to the binder system (EP-A-268918 and EP-A-632109).

Variant (4) (TiO₂/layer (E)/SiO_(z)/core/SiO_(z)/layer (E)/TiO₂:

As described above the SiO_(y)-coated metal platelets are coated withTiO₂ and then calcined in a non-oxidizing atmosphere. In this way anadditional layer (E) is produced besides the layer (B), which is formedby calcination of TiO₂/SiO_(y). It is assumed that calciningTiO₂/SiO_(y) in a non-oxidizing atmosphere produces an intermediatelayer that causes a change in the refractive index. However, thepossibility that the intermediate layer is not a continuous layer andthat, rather, only individual regions at the interface of TiO₂ andSiO_(y) undergo a conversion that causes a change in the refractiveindex cannot be ruled out. It is further assumed that the change in therefractive index is due to the reduction of TiO₂ by SiO_(y). Theprinciple according to the invention is based, therefore, on producing,by reduction of TiO₂ with SiO_(y), an intermediate layer that causes achange in the refractive index.TiO₂+SiO_(y)→SiO_(y+a)+TiO_(2−a)

Instead of TiO₂, another metal oxide that has a refractive index greaterthan 1.5 and that could be reduced by SiO_(y), such as, for example,Fe₂O₃, could also be used.

Accordingly, further preferred embodiments of the present invention aredirected to pigments having a layer structure,TiO₂/SiO_(z)/core/SiO_(z)/TiO₂, wherein the core is formed of a layer(B) or of a layer (B)/layer (A)/layer (B), wherein the layer (B) is onlyapplied to the plane-parallel faces, but not the side faces of layer(A), wherein the SiO_(y) layer is only present on the plane-parallelfaces, but not the side faces and the TiO₂ layer is applied to the wholesurface; as well as pigments having a layer structure, TiO₂/layer(E)/SiO_(y)/core/SiO_(y)/layer (E)/TiO₂, wherein the core is formed of alayer (B) or of a layer (B)/layer (A)/layer (B), wherein the layer (B)is only applied to the plane-parallel faces, but not the side faces oflayer (A), wherein the SiO_(y) layer and the layer (E) is only presenton the plane-parallel faces, but not the side faces and the TiO₂ layeris applied to the whole surface. In this embodiment the layer (A)consists preferably of aluminum. The layer (B) is preferably derivedfrom aluminum.

If desired, the TiO₂ can be reduced to titanium suboxides by usualmethods, as described, for example in U.S. Pat. No. 4,948,631, JPH4-20031, DE-A-19618562 and DE-A-198 43 014).

It is possible to obtain pigments that are more intense in color andmore transparent by applying, on top of the TiO₂ layer, a metal oxide of“low” refractive index, that is to say a refractive index smaller thanabout 1.65, such as SiO₂, Al₂O₃, AlOOH, B₂O₃ or a mixture thereofpreferably SiO₂ and applying a further Fe₂O₃ and/or TiO₂ layer on top ofthe latter layer. Such multi-coated interference pigments comprising asilicon oxide substrate and alternating metal oxide layers of with highand low refractive index can be prepared in analogy to the processesdescribed in WO98/53011 and WO99/20695.

Where appropriate, an SiO₂ (protective) layer can be applied on top ofthe titanium dioxide layer, for which the following method may be used:A soda water glass solution is metered in to a suspension of thematerial being coated, which suspension has been heated to about 50-100°C., especially 70-80° C. The pH is maintained at from 4 to 10,preferably from 6.5 to 8.5, by simultaneously adding 10% hydrochloricacid. After addition of the water glass solution, stirring is carriedout for 30 minutes.

It is, in addition, possible to modify the powder color of the pigmentby applying further layers such as, for example, colored metal oxides orBerlin Blue, compounds of transition metals, e.g. Fe, Cu, Ni, Co, Cr, ororganic compounds such as dyes or color lakes.

It is furthermore possible to subject the finished pigment to subsequentcoating or subsequent treatment which further increases the light,weather and chemical stability or which facilitates handling of thepigment, especially its incorporation into various media. For example,the procedures described in DE-A-22 15 191, DE-A-31 51 354, DE-A-32 35017, DE-A-33 34 598, DE-A-4030727, EP-A-649886, WO97/29059, WO99/57204,and U.S. Pat. No. 5,759,255 are suitable as subsequent treatment orsubsequent coating.

In addition, the pigment according to the invention can also be coatedwith poorly soluble, firmly adhering, inorganic or organic colorants.Preference is given to the use of color lakes and, especially, aluminumcolor lakes. For that purpose an aluminum hydroxide layer isprecipitated, which is, in a second step, laced by using a color lake(DE-A-24 29 762 and DE 29 28 287).

Furthermore, the pigment according to the invention may also have anadditional coating with complex salt pigments, especially cyan ferratecomplexes (EP-A-141 173 and DE-A-23 13 332).

After the SiO_(y)-coated metal flakes have been calcined, as describedin Variant (1), in a non-oxidizing gaseous atmosphere at a temperatureabove 600° C., preferably in the range of from 700 to 1100° C. for morethen 10 minutes, preferably for several hours, they can also be causedto react in a gas tight reactor heatable to a maximum of about 1500° C.,preferably in the form of loose material, with a carbon-containing gasselected from alkynes, for example acetylene, alkenes, for examplemethane, alkenes, aromatic compounds or the like, and mixtures thereofoptionally in admixture with an oxygen containing compound, such as, forexample, aldehydes, ketones, water, carbon monoxide, carbon dioxide orthe like, or mixtures thereof, at from 500 to 1500° C., preferably from500 to 1000° C., and advantageously with the exclusion of oxygen. Inorder to temper the reaction, an inert gas, for example argon or helium,may be admixed with the carbon-containing gas (WO03/68868).

At pressures of less than about 1 Pa the reaction generally alsoproceeds too slowly whereas, especially when the carbon-containing gasesare less reactive or are highly diluted with inert gas, it is perfectlypossible to operate at pressures of up to about 4000 bar, as areroutinely used, for example, in HIP (“hot isocratic pressing”) systems.

In such carbonization, it is possible for all of the SiO_(y) to bereacted to form SiC; preferably from 5 to 90% by weight of the SiO_(y)are reacted to form SiC. The temperature for the process of conversionof SiO_(y) to SiC is from 500° to 1500° C., preferably from 500° C. to1000° C., with a process duration of from about one hour to about twentyhours. The reaction takes place starting from the surface of theplane-parallel structures and accordingly results in a gradient ratherthan a sharp transition. This means that, in that embodiment, theSiC-containing layer consists of (SiO_(y))_(a) and (SiC)_(b), wherein0≦a<1 and 0<b≦1, with b being 1 and a being 0 close to the surface ofthe pigment and the amount of SiC approaching 0 close to the boundarywith the SiO_(y) substrate. The SiO_(y) structures are sufficientlyporous for such a reaction not to be limited only to the uppermost layerof SiO_(y) molecules.

Awarding to this process variant pigments having the following layerstructure, SiC/SiO_(y)/core/SiO_(y)/SiC, can be obtained, which can beconverted to pigments having the following layer structure,SiC/SiO_(z)/core/SiO_(z)/SiC, by calcination in the presence of oxygen.The pigments obtained by this process are new and are a further subjectof the present invention.

Instead of a layer of a metal oxide having a high index of refractionU.S. Pat. No. 6,524,381 materials, such as diamond-like carbon andamorphous carbon, can be deposited by plasma-assisted vacuum methods(using vibrating conveyors, rotating drum coaters, oscillatory drumcoaters, and free-fall chambers) as described, for example in U.S. Pat.No. 6,524,381, on the SiO_(z)-coated metal substrates.

Consequently, the present invention also relates to plane-parallelstructures (pigments) based on silicon oxide/metal substrates having ontheir surface a carbon layer especially a diamond-like carbon layerhaving a thickness of 5 to 150 nm, especially 20 to 50 nm.

In the method described, for example, in U.S. Pat. No. 6,015,597,diamond-like network (DLN) coatings are deposited onto particles fromcarbon-containing gases, such as, for example, acetylene, methane,butadiene and mixtures of these and optionally Ar, and optionally gasescontaining additional components by plasma deposition. Deposition occursat reduced pressures (relative to atmospheric pressure) and in acontrolled environment. A carbon rich plasma is created in a reactionchamber by applying an electric field to a carbon-containing gas.Particles to be coated are held in a vessel or container in the reactorand are agitated while in proximity to the plasma. Species within theplasma react on the particle surface to form covalent bonds, resultingin DLN on the surface of the particles.

The term “diamond-like network” (DLN) refers to amorphous films orcoatings comprised of carbon and optionally comprising one or moreadditional components selected from the group consisting of hydrogen,nitrogen, oxygen, fluorine, silicon, sulfur, titanium, and copper. Thediamond-like networks comprise approximately 30 to 100 atomic percentcarbon, with optional additional components making up the remainder

Metallic or non-metallic, inorganic platelet-shaped particles orpigments are effect pigments, (especially metal effect pigments orinterference pigments), that is to say, pigments that, besides impartingcolor to an application medium, impart additional properties, forexample angle dependency of the color (flop), lustre (not surface gloss)or texture. On metal effect pigments, substantially oriented reflectionoccurs at directionally oriented pigment particles. In the case ofinterference pigments, the imparting-imparting effect is due to thephenomenon of interference of light in thin, highly refractive layers.

The pigments according to the invention can be used for all customarypurposes, for example for coloring polymers in the mass, coatings(including effect finishes, including those for the automotive sector)and printing inks (including offset printing, intaglio printing,bronzing and flexographic printing), and also, for example, forapplications in cosmetics, in ink-jet printing, for dyeing textiles,glazes for ceramics and glass as well as laser marking of papers andplastics. Such applications are known from reference works, for example“Industrielle Organische Pigmente” (W. Herbst and K. Hunger, VCHVerlagsgesellschaft mbH. Weinheim/New York, 2nd, completely revisededition, 1995).

When the pigments according to the invention are interference pigments(effect pigments), they are goniochromatic and result in brilliant,highly saturated (lustrous) colors. They are accordingly very especiallysuitable for combination with conventional, transparent pigments, forexample organic pigments such as, for example, diketopyrrolopyrroles,quinacridones, dioxazines, perylenes, isoindolinones etc., it beingpossible for the transparent pigment to have a similar color to theeffect pigment. Especially interesting combination effects are obtained,however, in analogy to, for example, EP-A-388 932 or EP-A402 943, whenthe color of the transparent pigment and that of the effect pigment arecomplementary.

The pigments according to the invention can be used with excellentresults for pigmenting high molecular weight organic material.

The high molecular weight organic material for the pigmenting of whichthe pigments or pigment compositions according to the invention may beused may be of natural or synthetic origin. High molecular weightorganic materials usually have molecular weights of about from 10³ to10⁸ g/mol or even more. They may be, for example, natural resins, dryingoils, rubber or casein, or natural substances derived therefrom, such aschlorinated rubber, oil-modified alkyd resins, viscose, cellulose ethersor esters, such as ethylcellulose, cellulose acetate, cellulosepropionate, cellulose acetobutyrate or nitrocellulose, but especiallytotally synthetic, organic polymers (thermosetting plastics andthermoplastics), as are obtained by polymerisation, polycondensation orpolyaddition. From the class of the polymerisation resins there may bementioned, especially, polyolefins, such as polyethylene, polypropyleneor polyisobutylene, and also substituted polyolefins, such aspolymerisation products of vinyl chloride, vinyl acetate, styrene,acrylonitrile, acrylic acid esters, methacrylic acid esters orbutadiene, and also copolymerisation products of the said monomers, suchas especially ABS or EVA.

From the series of the polyaddition resins and polycondensation resinsthere may be mentioned, for example, condensation products offormaldehyde with phenols, so-called phenoplasts, and condensationproducts of formaldehyde with urea, thiourea or melamine, so-calledaminoplasts, and the polyesters used as surface-coating resins, eithersaturated, such as alkyd resins, or unsaturated, such as maleate resins;also linear polyesters and polyamides, polyurethanes or silicones.

The said high molecular weight compounds may be present singly or inmixtures, in the form of plastic masses or melts. They may also bepresent in the form of their monomers or in the polymerised state indissolved form as film-formers or binders for coatings or printing inks,such as, for example, boiled linseed oil, nitrocellulose, alkyd resins,melamine resins and urea-formaldehyde resins or acrylic resins.

Depending on the intended purpose it has proved advantageous to use theeffect pigments or effect pigment compositions according to theinvention as toners or in the form of preparations. Depending on theconditioning method or intended application, it may be advantageous toadd certain amounts of texture-improving agents to the effect pigmentbefore or after the conditioning process, provided that this has noadverse effect on use of the effect pigments for coloring high molecularweight organic materials, especially polyethylene. Suitable agents are,especially, fatty acids containing at least 18 carbon atoms, for examplestearic or behenic acid, or amides or metal salts thereof, especiallymagnesium salts, and also plasticisers, waxes, resin acids, such asabietic acid, rosin soap, alkylphenols or aliphatic alcohols, such asstearyl alcohol, or aliphatic 1,2-dihydroxy compounds containing from 8to 22 carbon atoms, such as 1,2-dodecanediol, and also modifiedcolophonium maleate resins or fumaric acid colophonium resins. Thetexture-improving agents are added in amounts of preferably from 0.1 to30% by weight, especially from 2 to 15% by weight, based on the endproduct.

The (effect) pigments according to the invention can be added in anytinctorially effective amount to the high molecular weight organicmaterial being pigmented. A pigmented substance composition comprising ahigh molecular weight organic material and from 0.01 to 80% by weight,preferably from 0.1 to 30% by weight, based on the high molecular weightorganic material, of an pigment according to the invention isadvantageous. Concentrations of from 1 to 20% by weight, especially ofabout 10% by weight, can often be used in practice.

High concentrations, for example those above 30% by weight, are usuallyin the form of concentrates (“masterbatches”) which can be used ascolorants for producing pigmented materials having a relatively lowpigment content, the pigments according to the invention having anextraordinarily low viscosity in customary formulations so that they canstill be processed well.

For the purpose of pigmenting organic materials, the effect pigmentsaccording to the invention may be used singly. It is, however, alsopossible, in order to achieve different hues or color effects, to addany desired amounts of other imparting-imparting constituents, such aswhite, colored, black or effect pigments, to the high molecular weightorganic substances in addition to the effect pigments according to theinvention. When colored pigments are used in admixture with the effectpigments according to the invention, the total amount is preferably from0.1 to 10% by weight, based on the high molecular weight organicmaterial.

Especially high goniochromicity is provided by the preferred combinationof an effect pigment according to the invention with a colored pigmentof another color, especially of a complementary color, with colorationsmade using the effect pigment and colorations made using the coloredpigment having, at a measurement of 10°, a difference in hue (ΔH*) offrom 20 to 340, especially from 150 to 210.

Preferably, the effect pigments according to the invention are combinedwith transparent colored pigments, it being possible for the transparentcolored pigments to be present either in the same medium as the effectpigments according to the invention or in a neighbouring medium. Anexample of an arrangement in which the effect pigment and the coloredpigment are advantageously present in neighbouring media is amulti-layer effect coating.

The pigmenting of high molecular weight organic substances with thepigments according to the invention is carried out, for example, byadmixing such a pigment, where appropriate in the form of a masterbatch,with the substrates using roll mills or mixing or grinding apparatuses.The pigmented material is then brought into the desired final form usingmethods known per se, such as calendering, compression moulding,extrusion, coating, pouring or injection moulding. Any additivescustomary in the plastics industry, such as plasticisers, fillers orstabilisers, can be added to the polymer, in customary amounts, beforeor after incorporation of the pigment. In particular, in order toproduce non-rigid shaped articles or to reduce their brittleness, it isdesirable to add plasticisers, for example esters of phosphoric acid,phthalic acid or sebacic acid, to the high molecular weight compoundsprior to shaping.

For pigmenting coatings and printing inks, the high molecular weightorganic materials and the effect pigments according to the invention,where appropriate together with customary additives such as, forexample, fillers, other pigments, siccatives or plasticisers, are finelydispersed or dissolved in the same organic solvent or solvent mixture,it being possible for the individual components to be dissolved ordispersed separately or for a number of components to be dissolved ordispersed together, and only thereafter for all the components to bebrought together.

Dispersing an effect pigment according to the invention in the highmolecular weight organic material being pigmented, and processing apigment composition according to the invention, are preferably carriedout subject to conditions under which only relatively weak shear forcesoccur so that the effect pigment Is not broken up into smaller portions.

Plastics comprising the pigment of the invention in amounts of 0.1 to50% by weight, in particular 0.5 to 7% by weight. In the coating sector,the pigments of the invention are employed in amounts of 0.1 to 10% byweight. In the pigmentation of binder systems, for example for paintsand printing inks for intaglio, offset or screen printing, the pigmentis incorporated into the printing ink in amounts of 0.1 to 50% byweight, preferably 5 to 30% by weight and in particular 8 to 15% byweight.

The colorations obtained, for example in plastics, coatings or printinginks, especially in coatings or printing inks, more especially incoatings are distinguished by excellent properties, especially byextremely high saturation, outstanding fastness properties and highgoniochromicity.

When the high molecular weight material being pigmented is a coating, itis especially a speciality coating, very especially an automotivefinish.

The effect pigments according to the invention are also suitable formaking-up the lips or the skin and for coloring the hair or the nails.

The invention accordingly relates also to a cosmetic preparation orformulation comprising from 0.0001 to 90% by weight of a pigment,especially an effect pigment, according to the invention and from 10 to99.9999% of a cosmetically suitable carrier material, based on the totalweight of the cosmetic preparation or formulation.

Such cosmetic preparations or formulations are, for example, lipsticks,blushers, foundations, nail varnishes and hair shampoos.

The pigments may be used singly or in the form of mixtures. It is, inaddition, possible to use pigments according to the invention togetherwith other pigments and/or colorants, for example in combinations asdescribed hereinbefore or as known in cosmetic preparations. Thecosmetic preparations and formulations according to the inventionpreferably contain the pigment according to the invention in an amountfrom 0.005 to 50% by weight, based on the total weight of thepreparation.

Suitable carrier materials for the cosmetic preparations andformulations according to the invention include the customary materialsused in such compositions.

The cosmetic preparations and formulations according to the inventionmay be in the form of, for example, sticks, ointments, creams,emulsions, suspensions, dispersions, powders or solutions. They are, forexample, lipsticks, mascara preparations, blushers, eye-shadows,foundations, eyeliners, powder or nail varnishes.

If the preparations are in the form of sticks, for example lipsticks,eye-shadows, blushers or foundations, the preparations consist for aconsiderable part of fatty components, which may consist of one or morewaxes, for example ozokerite, lanolin, lanolin alcohol, hydrogenatedlanolin, acetylated lanolin, lanolin wax, beeswax, candelilla wax,microcrystalline wax, carnauba wax, cetyl alcohol, stearyl alcohol,cocoa butter, lanolin fatty acids, petrolatum, petroleum jelly, mono-,di- or tri-glycerides or fatty esters thereof that are solid at 25° C.,silicone waxes, such as methyloctadecane-oxypolysiloxane andpoly(dimethylsiloxy)-stearoxysiloxane, stearic acid monoethanolamine,colophane and derivatives thereof, such as glycol abietates and glycerolabietates, hydrogenated oils that are solid at 25° C., sugar glyceridesand oleates, myristates, lanolates, stearates and dihydroxystearates ofcalcium, magnesium, zirconium and aluminum.

The fatty component may also consist of a mixture of at least one waxand at least one oil, in which case the following oils, for example, aresuitable: paraffin oil, purcelline oil, perhydrosqualene, sweet almondoil, avocado oil, calophyllum oil, castor oil, sesame oil, jojoba oil,mineral oils having a boiling point of about from 310 to 410° C.,silicone oils, such as dimethylpolysiloxane, linoleyl alcohol, linolenylalcohol, oleyl alcohol, cereal grain oils, such as wheatgerm oil,isopropyl lanolate, isopropyl palmitate, isopropyl myristate, butylmyristate, cetyl myristate, hexadecyl stearate, butyl stearate, decyloleate, acetyl glycerides, octanoates and decanoates of alcohols andpolyalcohols, for example of glycol and glycerol, ricinoleates ofalcohols and polyalcohols, for example of cetyl alcohol, isostearylalcohol, isocetyl lanolate, isopropyl adipate, hexyl laurate and octyldodecanol.

The fatty components in such preparations in the form of sticks maygenerally constitute up to 99.91% by weight of the total weight of thepreparation.

The cosmetic preparations and formulations according to the inventionmay additionally comprise further constituents, such as, for example,glycols, polyethylene glycols, polypropylene glycols, monoalkanolamides,non-coloured polymeric, inorganic or organic fillers, preservatives, UVfilters or other adjuvants and additives customary in cosmetics, forexample a natural or synthetic or partially synthetic di- ortri-glyceride, a mineral oil, a silicone oil, a wax, a fatty alcohol, aGuerbet alcohol or ester thereof, a lipophilic functional cosmeticactive ingredient, including sun-protection filters, or a mixture ofsuch substances.

A lipophilic functional cosmetic active ingredient suitable for skincosmetics, an active ingredient composition or an active ingredientextract is an ingredient or a mixture of ingredients that is approvedfor dermal or topical application. The following may be mentioned by wayof example:

-   -   active ingredients having a cleansing action on the skin surface        and the hair; these include all substances that serve to cleanse        the skin, such as oils, soaps, synthetic detergents and solid        substances;    -   active ingredients having a deodorising and        perspiration-inhibiting action: they include antiperspirants        based on aluminium salts or zinc salts, deodorants comprising        bactericidal or bacteriostatic deodorising substances, for        example triclosan, hexachlorophene, alcohols and cationic        substances, such as, for example, quaternary ammonium salts, and        odour absorbers, for example ®Grillocin (combination of zinc        ricinoleate and various additives) or triethyl citrate        (optionally in combination with an antioxidant, such as, for        example, butyl hydroxytoluene) or ion-exchange resins;    -   active ingredients that offer protection against sunlight (UV        filters): suitable active ingredients are filter substances        (sunscreens) that are able to absorb UV radiation from sunlight        and convert it into heat; depending on the desired action, the        following light-protection agents are preferred:        light-protection agents that selectively absorb sunburn-causing        high-energy UV radiation in the range of approximately from 280        to 315 nm (UV-B absorbers) and transmit the longer-wavelength        range of, for example, from 315 to 400 nm (UV-A range), as well        as light-protection agents that absorb only the        longer-wavelength radiation of the UV-A range of from 315 to 400        nm (UV-A absorbers); suitable light-protection agents are, for        example, organic UV absorbers from the class of the        p-aminobenzoic acid derivatives, salicylic acid derivatives,        benzophenone derivatives, dibenzoylmethane derivatives, diphenyl        acrylate derivatives, benzofuran derivatives, polymeric UV        absorbers comprising one or more organosilicon radicals,        cinnamic acid derivatives, camphor derivatives,        trianilino-s-triazine derivatives, phenyl-benzimidazolesulfonic        acid and salts thereof, menthyl anthranilates, benzotriazole        derivatives, and/or an inorganic micropigment selected from        aluminium oxide- or silicon dioxide-coated TiO₂, zinc oxide or        mica;    -   active ingredients against insects (repellents) are agents that        are intended to prevent insects from touching the skin and        becoming active there; they drive insects away and evaporate        slowly; the most frequently used repellent is diethyl toluamide        (DEET); other common repellents will be found, for example, in        “Pflegekosmetik” (W. Raab and U. Kindl, Gustav-Fischer-Verlag        Stuttgart/New York,1991) on page 161;    -   active ingredients for protection against chemical and        mechanical influences: these include all substances that form a        barrier between the skin and external harmful substances, such        as, for example, paraffin oils, silicone oils, vegetable oils,        PCL products and lanolin for protection against aqueous        solutions, film-forming agents, such as sodium alginate,        triethanolamine alginate, polyacrylates, polyvinyl alcohol or        cellulose ethers for protection against the effect of organic        solvents, or substances based on mineral oils, vegetable oils or        silicone oils as “lubricants” for protection against severe        mechanical stresses on the skin;    -   moisturising substances: the following substances, for example,        are used as moisture-controlling agents (moisturisers): sodium        lactate, urea, alcohols, sorbitol, glycerol, propylene glycol,        collagen, elastin and hyaluronic acid;    -   active ingredients having a keratoplastic effect: benzoyl        peroxide, retinoic acid, colloidal sulfur and resorcinol;    -   antimicrobial agents, such as, for example, triclosan or        quaternary ammonium compounds;    -   oily or oil-soluble vitamins or vitamin derivatives that can be        applied dermally: for example vitamin A (retinol in the form of        the free acid or derivatives thereof) panthenol pantothenic        acid, folic acid, and combinations thereof, vitamin E        (tocopherol), vitamin F; essential fatty acids; or niacinamide        (nicotinic acid amide);    -   vitamin-based placenta extracts: active ingredient compositions        comprising especially vitamins A, C, E, B₁, B₂, B₆, B₁₂, folic        acid and biotin, amino acids and enzymes as well as compounds of        the trace elements magnesium, silicon, phosphorus, calcium,        manganese, iron or copper;    -   skin repair complexes: obtainable from inactivated and        disintegrated cultures of bacteria of the bifidus group;    -   plants and plant extracts: for example arnica, aloe, beard        lichen, ivy, stinging nettle, ginseng, henna, camomile,        marigold, rosemary, sage, horsetail or thyme;    -   animal extracts: for example royal jelly, propolis, proteins or        thymus extracts;    -   cosmetic oils that can be applied dermally: neutral oils of the        Miglyol 812 type, apricot kernel oil, avocado oil, babassu oil,        cottonseed oil, borage oil, thistle oil, groundnut oil,        gamma-oryzanol, rosehip-seed oil, hemp oil, hazelnut oil,        blackcurrant-seed oil, jojoba oil, cherry-stone oil, salmon oil,        linseed oil, cornseed oil, macadamia nut oil, almond oil,        evening primrose oil, mink oil, olive oil, pecan nut oil, peach        kernel oil, pistachio nut oil, rape oil, rice-seed oil, castor        oil, safflower oil, sesame oil, soybean oil, sunflower oil, tea        tree oil, grapeseed oil or wheatgerm oil.

The preparations in stick form are preferably anhydrous but may incertain cases comprise a certain amount of water which, however, ingeneral does not exceed 40% by weight, based on the total weight of thecosmetic preparation.

If the cosmetic preparations and formulations according to the inventionare in the form of semi-solid products, that is to say in the form ofointments or creams, they may likewise be anhydrous or aqueous. Suchpreparations and formulations are, for example, mascaras, eyeliners,foundations, blushers, eye-shadows, or compositions for treating ringsunder the eyes.

If, on the other hand, such ointments or creams are aqueous, they areespecially emulsions of the water-in-oil type or of the oil-in-watertype that comprise, apart from the pigment, from 1 to 98.8% by weight ofthe fatty phase, from 1 to 98.8% by weight of the aqueous phase and from0.2 to 30% by weight of an emulsifier.

Such ointments and creams may also comprise further conventionaladditives, such as, for example, perfumes, antioxidants, preservatives,gel-forming agents, UV filters, colorants, pigments, pearlescent agents,non-coloured polymers as well as inorganic or organic fillers. If thepreparations are in the form of a powder, they consist substantially ofa mineral or inorganic or organic filler such as, for example, talcum,kaolin, starch, polyethylene powder or polyamide powder, as well asadjuvants such as binders, colorants, etc.

Such preparations may likewise comprise various adjuvants conventionallyemployed in cosmetics, such as fragrances, antioxidants, preservativesetc.

If the cosmetic preparations and formulations according to the inventionare nail varnishes, they consist essentially of nitrocellulose and anatural or synthetic polymer in the form of a solution in a solventsystem, it being possible for the solution to comprise other adjuvants,for example pearlescent agents.

In that embodiment, the coloured polymer is present in an amount ofapproximately from 0.1 to 5% by weight.

The cosmetic preparations and formulations according to the inventionmay also be used for colouring the hair, in which case they are used inthe form of shampoos, creams or gels that are composed of the basesubstances conventionally employed in the cosmetics industry and apigment according to the invention.

The cosmetic preparations and formulations according to the inventionare prepared in conventional manner, for example by mixing or stirringthe components together, optionally with heating so that the mixturesmelt.

The Examples that follow illustrate the invention without limiting thescope thereof. Unless otherwise indicated, percentages and parts arepercentages and parts by weight, respectively.

EXAMPLES Example 1

A layer of NaCl having a thickness of about 50 nm is evaporated in avacuum chamber on a metal carrier at a pressure below about 10-2 Pa.Then at the same pressure the following layers are depositedsuccessively: SiO, Al and SiO, wherein a film having the following layerstructure is formed on the metal carrier:SiO(270 nm)/Al(40 nm)/SiO(270 nm)

Subsequently, the separating agent is dissolved in deionised water, the(SiO/Al/SiO) layer, which is insoluble, breaks up into flakes. Thesuspension is, at atmospheric pressure, concentrated by filtration andrinsed several times with deionised water in order to remove Na⁺ and Cl⁻ions that are present. After drying SiO_(y)-coated aluminum flakes areobtained, which show bright metallic colors.

The obtained SiO_(y)-coated aluminum flakes are heated in an argonatmosphere with a temperature gradient of 100° C./minute up to 750° C.,i.e. above the melting point of aluminum. The obtained flakes show amatt green/yellow color and are partly transparent.

The thus obtained pigments are coated with TiO₂ (20 nm) by a wetchemical method: The SiO_(y)-coated aluminum flakes are suspended infully deionized water and heated to 75° C. To this suspension an aqueoussolution of TiCl₄ is metered. The pH is kept constant at pH=2.2 by meansof 32% sodium hydroxide solution. After this solution has been added,the mixture is stirred for a further approximately 30 minutes at 75° C.The thus obtained pigments are characterized by bright green/yellowcolors and show depending on the viewing angle color flop.

To further increases the light, weather and chemical stability, thepigments may be oxidized using air at a temperature of 200° C. in theform of loose material in a fluidized bed.

Example 2

In a vacuum chamber the following layers are successively sublimed on aglass substrate at a pressure below about 10⁻² Pa: TiO₂ (50 nm), SiO(270 nm), Al (50 nm), SiO (270 nm) and TiO₂ (50 nm). One specimen isused as reference specimen (RS), the other specimen (S) is heated in anargon atmosphere 0.5 hours at 700° C.

The reflection color (CIE-L*C*h) of the specimen (S) and the referencespecimen (RS) is determined at irradiation with standard illuminant D₆₅under a 10°, 30° and 50° observation angle: Calci- Viewing AngleSpecimen nation [Grad] L* a* b* c* h RS no 10 98 9.7 5.2 11 28.1 RS no30 99.5 0.2 15.8 15.8 89.1 RS no 50 100 −8.5 16.5 18.6 117 S yes 10 70−6.4 −3.0 7 205 S yes 30 68.4 −11.7 −7.6 13.9 213 S yes 50 64.8 −13.8−16.8 21.7 230.6

1. A pigment, comprising (A) optionally a layer consisting of a metal,(B) at least one layer, which is located between the layers (A) and (C),if a layer (A) is present, and consists of the metal, silicon (Si) andoxygen (O), and (C) optionally a layer consisting of SiO_(z) on layer(B), wherein 0.70≦z≦2.0.
 2. A pigment according to claim 1, comprising(B) at least one layer, which consists of the metal, silicon (Si) andoxygen (O), and (C) at least one layer consisting of SiO_(z) on layer(B), wherein 0.70≦z≦2.0.
 3. The pigment according to claim 1, comprising(C1) a layer consisting of SiO_(z), (B) at least one layer, which islocated between the layers (C1) and (C2), and consists of the metal,silicon (Si) and oxygen (O), (C2) at least one layer consisting ofSiO_(z) on layer (B), wherein 0.70≦z≦2.0.
 4. The pigment according toclaim 3, comprising (D) an additional layer of a material having a highindex of refraction.
 5. The pigment according to claim 4, comprising(D1) a layer of a material having a high index of refraction, especiallyTiO₂, (C1) a layer consisting of SiO_(z), (B) at least one layer, whichis located between the layers (C1) and (C2), and consists of the metal,silicon (Si) and oxygen (O), (C2) a layer consisting of SiO_(z), and(D2) a layer of a material having a high index of refraction, wherein0.70≦z≦2.0.
 6. The pigment according to claim 1, wherein the metal isselected from Ag, Al, Cu, Cr, Mo, Ni, Ti, or alloys thereof.
 7. Thepigment according to claim 3 having the following layer structure:TiO₂/SiO_(z)/core/SiO_(z)/TiO₂, wherein the core is formed of a layer(B) or of a layer (B)/layer (A)/layer (B), wherein the layer (B) ispresent on the plane-parallel faces, but not the side faces of layer(A), wherein the SiO_(z) layer is only present on the plane-parallelfaces, but not the side faces and the TiO₂ layer is applied to the wholesurface; SiC/SiO_(z)/core/SiO_(z)/SiC, or C/SiO_(z)/core/SiO_(z)/C,wherein 0.70≦z≦2.0.
 8. A pigment, obtained by calcination ofplane-parallel structures (flakes), comprising (A) at least one layerconsisting of a metal and (C) at least one layer consisting of SiO with0.70≦z≦2.0, in a non-oxidizing atmosphere and optionally coating of theobtained flakes with further layers.
 9. Plane-parallel structures,comprising (A) a layer consisting of a metal, and (C) at least one layerconsisting of SiO_(z), wherein 0.70≦z≦2.0.
 10. (canceled)
 11. A textile,coating, paint, printing ink, plastic, composition, cosmeticpreparation, or a glaze for ceramic and glass, comprising a pigmentaccording to claim
 1. 12. (canceled)
 13. A pigment according to claim 1,wherein 1.40≦z≦2.0.
 14. A pigment according to claim 2, wherein1.40≦z≦2.0.
 15. The pigment according to claim 4, wherein the materialcomprising the additional layer (D) having a high index of refraction isselected from the group consisting of TiO₂, amorphous carbon, diamondlike carbon and silicon carbide.
 16. A pigment according to claim 5,wherein 1.40≦z≦2.0.
 17. The pigment according to claim 5, wherein thematerial comprising layers (D1) and (D2) is TiO₂.
 18. A pigmentaccording to claim 9, wherein the metal of layer (A) is aluminum.
 19. Apigment according to claim 9, wherein 1.40≦z≦2.0.
 20. A textile,coating, paint, printing ink, plastic, composition, cosmeticpreparation, or a glaze for ceramic and glass, comprising a pigmentaccording to claim
 2. 21. A textile, coating, paint, printing ink,plastic, composition, cosmetic preparation, or a glaze for ceramic andglass, comprising a pigment according to claim
 8. 22. A textile,coating, paint, printing ink, plastic, composition, cosmeticpreparation, or a glaze for ceramic and glass, comprising a pigmentaccording to claim 13.